1. Field of the Invention
The present invention relates to a method of and apparatus for unfolding a sheet metal part employing a CAD apparatus.
2. Description of the Prior Art
Referring to FIG. 8 showing an exemplary sheet metal part unfolding procedure in a conventional sheet metal part unfolding method employing a CAD apparatus, the conventional sheet metal part unfolding method comprises a sheet metal part separating step S31, a surface entity extracting step S32, and an unfolding step S33.
In the sheet metal part separating step S31, the entities of the three-dimensional model 1 are separated into a sheet metal part surface 2, a sheet metal part surface 3, sheet metal part surface interconnecting entities 4 through the conversational operation of a CAD apparatus. In the surface entity extracting step S32, either the sheet metal part surface 2 or 3 is extracted as a part surface pattern 12. In the unfolding step S33, unfolding reference entities and 6, an unfolding axis entity 7 and unfolding entities 8 to 11 are specified through the conversational operation of the CAD apparatus to produce an unfolded pattern 13.
Referring to FIG. 9, a conventional conversational three-dimensional sheet metal part unfolding CAD apparatus comprises a pattern display unit 21, a pattern operating data input unit 22, a position data input unit 23, a pattern processing unit 24, a pattern memory unit 25 and a sheet metal part unfolding unit 26.
In operation, a pattern operating command, such as a pattern shifting command or a pattern deleting command is input through the conversational operation of the pattern operating data input unit 22, and position data is input by operating the position data input unit 23. Upon the reception of the pattern operating command and the position data, the pattern processing unit 24 processes the pattern operating command and the position data, and inputs the results of operation to the pattern memory unit 25, produces display data to be displayed, and inputs the display data to the pattern display unit 21. Then, the pattern display unit 21 displays the three-dimensional model 1 shown in FIG. 8. The pattern memory unit 25 stores pattern entity names, such as circles and lines, and the pattern position. The sheet metal part unfolding unit 26 executes the sheet metal part unfolding steps S31, S32 and S33 shown in FIG. 8 to produce the unfolded pattern 13.
However, in carrying out such a conventional sheet metal part unfolding method employing a CAD apparatus, pattern entity specifications for unfolding the bends of a sheet metal part, and bend elongation specifications for specifying the elongation of bends in unfolding a sheet metal part are required, which require many steps of a conversational operation and many steps of a bend elongation calculating operation.